This invention relates to aluminum metal-matrix composites for use in tribological applications.
The major drawback of aluminum alloys in tribological applications is their poor resistance to seizure and galling. Aluminum has a tendency to smear the counterface during sliding contact. Because of this, aluminum alloys are rarely used in applications involving dry sliding contact.
Attempts have been made to improve the tribological performance of aluminum alloys by dispersing solid lubricant particles, such as graphite, through the alloy matrix. The friction coefficient of commercial aluminum alloys is relatively high, generally about 0.5-0.6. Dispersion of graphite through such a matrix can reduce the friction coefficient to about 0.2. However, graphite loses its lubricity in dry environments. Thus, aluminum-graphite composites have limited uses: (a) in environments with relative humidity in excess of 50%, and (b) in boundary lubrication regimes. What is desired is a self-lubricating aluminum alloy bearing material which can be used in vacuum, dry or moist environments.
Accordingly, it is an object of this invention to provide a self-lubricating aluminum alloy bearing material which can be used in vacuum, dry or moist environments.
Other objects and advantages of the present invention will be apparent to those skilled in the art.